Chlorine dioxide is known to be a disinfectant, as well as a strong oxidizing agent. The bactericidal, algaecidal, fungicidal, bleaching, and deodorizing properties of chlorine dioxide are also well known. Therapeutic and cosmetic applications for chlorine dioxide are known. For example, U.S. Pat. No. 6,280,716 describes the use of stabilized chlorine dioxide solutions for the treatment of vaginal itching. U.S. Pat. No. 7,029,705 describes the use of stabilized chlorine dioxide solutions for a method of nasal hygiene.
The traditional method for preparing chlorine dioxide involves reacting sodium chlorite with gaseous chlorine (Cl2(g)), hypochlorous acid (HOCl), or hydrochloric acid (HCl). The reactions proceed at much greater rates in acidic medium, so substantially all traditional chlorine dioxide generation chemistry results in an acidic product solution having a pH below 3.5.
Chlorine dioxide may also be prepared from chlorate anion by either acidification or a combination of acidification and reduction. At ambient conditions, all reactions using chlorate anion require strongly acidic conditions; most commonly in the range of 7-9 N. Heating of the reagents to higher temperature and continuous removal of chlorine dioxide from the product solution can reduce the acidity needed to less than 1 N.
A method of preparing chlorine dioxide in situ uses a solution referred to as “stabilized chlorine dioxide.” Stabilized chlorine dioxide solutions contain little or no chlorine dioxide, but rather, consist substantially of sodium chlorite at neutral or slightly alkaline pH. Addition of an acid to the sodium chlorite solution activates the sodium chlorite, and chlorine dioxide is generated in situ in the solution. The resulting solution is acidic. Typically, the extent of sodium chlorite conversion to chlorine dioxide is low, and a substantial quantity of sodium chlorite remains in the solution.
The current literature summarized above describes the use of chlorine dioxide compositions and methods that are damaging to biological tissues. Methods, compositions, devices, and systems for using chlorine dioxide for treatment of biological tissue in which biological tissue is not damaged are needed.